Bit shank and chuck



(No Model.)

M. LANDREW. BIT SHANK AND CHUCK.

No. 525,573. Patented Sept. 4, 1894.

FHELZ.

FIEJ

UNITED STATES PATENT OFFICE.

MOSES L. ANDREW, OF DELHI, OHIO.

BIT SIHANK AN'DCHUCK.

SPECIFICATION forming part of Letters Patent No. 525,573, datedSeptember 4, 1894;

Application filed February 25, 1892. Serial No. :22,?26. (No model.)

To all whom, it may concern.-

Be it known that I, Mosns L. ANDREW, a citizen of the United States, anda resident of Delhi, in the county of Hamilton and State of Ohio, haveinvented certain new and useful Improvements in Bit Shanks and Chucks,of which the following is a specification.

My invention relates to boring tools, and especially to the shank, andmeans for holding the shanks.

The object of my invention is to provide means to securely hold bits,especially those having tapered shanks, securely without injury to theshanks, by which means the shanks of bits or boring tools which havebeen rendered worthless by the means formerly emplo'yed for holdingthem, may be restored and used until the cutting portion of the bit isworn out.

Metal drilling bits for heavy or accurate work are usually made withtapered shanks to insure a close fit to the chuck, and absolutelyaccurate axial alignment with the spindle. To prevent these bits fromturning in the holder they are commonlyformed with a flat, or angular,end to entera corresponding recess in the holder, and in addition tothis it is found necessary when such shank is applied to a boring barfor dressing the under side of a hole, or forming a countersink, or thebit or bar is used in an upright drill press,

that set screws must be employed to prevent the bit or bar from beingpulled out. The set screws necessarily mar or injury the shank as theymust be forced very firmly upon the shank to prevent the bit fromturning.

It is the experience of every user of metal drills, that a very largepercentage of the most expensive drills are rendered worthless by theangular end of the shank being twisted 01f, or the shanks being soinjured by set screws as to prevent absolutely true centering of thebit, long before the cutting body of the bit is near worn out.

By my invention I provide means to hold the bits truly and firmlyuntil'worn out, and also to render the formerly worthless bits as veflfective as new ones.

The invention consists in the construction,

which will be hereinafter particularly described in connection with theaccompanying A drawings, and will then be particularly referred to andpointed out in the claims.

Referring to the drawings in which like parts are indicated by similarreference letterswherever they occur throughout the various views:Figure 1. is a perspective view of my improved chuck with the standardtaper shank formed according to my invention. Fig. 2. is a diametricalsectional view of my improvements applied to a straight shank bit. Fig.3. is a view in longitudinal diametrical section of my improvedchuck,and a cutter bar; my improved shank is secured therein; the cutter barand key for holding it is shown in elevation. Fig. 4:. is a transversesectional view, taken through line a, a; Fig. 3.

The chuck .body shown in Fig. 2. is substantially the same as the bodyof the chuck in my Patent No. 403,083, of May 14, 1889, but the shank ofthe bit, and edge of the locking key bearing upon it, is constructedaccording tomy present invention.

Referring to the parts by reference letters and particularly to Figs. 3and 4 A, is the head of the chuck, which has formed integral with it thetapered shank A. The intermediate portion of the head A, is cone shapedat a, and the forward end is a reduced screw threaded neck a.

B is a cap, interiorly screw tapped at its forward end to engage thescrew threaded neck a, of the head. The rear portion of the cap base ismade flaring counter to the cone shaped portion a, of the head A. Thecone shaped part a, is radially slotted to receive thehardene'd steelkey 0, the outer edge of which is beveled to the same taper as the coneshaped portion a of the head A, and the flaring inner Wall of the screwcap. The inner edge of the key is rounded as seen clearly in Fig. 4. toenter the circular depression (1?, in the shank of the chuck, bit, orcutter bar D. The longitudinal lower edge of the key is inclined fromits front to rear end at the same angle to the axis of the head and bit,as the circular depression of the shanks. The depression a in the shankis formed by a milling tool and is made deeper at its end near theshoulder, than at the rear end, that is the bottom of the depression isabout one thirty second of an inch nearer the axis of the bit IOO orshank at its inner end, than it is at the end of the shank, so that whenthe key is forced into the depression (1. it is impossible to pull theshank out until the cap isloosened to free the key 0. This feature ofthe rearwardl y fiarin g key seat is especially valuable in use withboring bars as D, Fig. 3. as it prevents the bar from being pulled outwhen dressing the under side of a hole or forming a countersink as seenin Fig. 3. in which E, is the article being dressed, F, the customarycutter, held in a slot cut through the cutter bar D, by the keyf.

The key 0, snugly fits the depression g9,

and when forced to place as shown, locks the shank to the holder asfirmly as if the shank and holder were a single piece, and the peripheryof the shank is not marred or injured in the least. i

The perforation a through the head A, is to admit a drift to start theshank outwardly when it is desired to remove the bit chuck or cutterbar.

It is obvious that the circular and rearwardly inclined grooved shank A,may be more firmly held by an ordinary round pointed set screw than theordinary shanks now in common use, and with less injury to the bit, andthat with the use of said shank and my set key, and screw cap, theangular end on the common taper shank may be omitted when the bit ismade, and the labor of so grooving the shank is much less than the laborof forming the shank with a taper end.

I prefer to make the longitudinal and rearwardly inclined groove acircular in trans verse section, because it is easier made, and so made,the boring tool may be readily adapted to the common chucks in which aset screw is employed, in such case it would only be necessary to formthe point of the screw counter to the curve of the groove, but I do notdesire to limit myself to such specific construction as any groove whichinclines outwardly from the axis as it extends toward the end of theshank, would attain the same result in kind but not in degree.

In Fig. 2. the cap B, is screw threaded at the rear end and within theforward end is fitted the flaring ring E the same as (a: at) in myformer patent. This form of cap, screw threaded connection between thecap and head and the flaring clamping ring may of course be employed inplace of the flaring mouthed cap B, shown in Fig. 3.

I am aware that it is not new to formin bit shanks slots, key seats andgrooves parallel to the axis of the bit and hence make no claim to a bitshank so constructed.

What I claim as new, and desire to secure by Letters Patent, is-

l. The combination of the taper shank havinga longitudinally grooved keyseat formed in it, said key seat being deeper near the shoul+ der anddiverging rearwardly from the axis toward the end of the shank, theradially slotted tool holding head, axially bored to receive said shank,the key fitted to slide in said slot and bear upon the inclined seat inthe shank, ,the cap to fit over the head and bear upon the outer edge ofthe key, for the purpose of forcing the key upon its seat when turned inone direction and releasing it therefrom when turned in the oppositedirection, substantially as shown and described.

2. The combination substantiallyas herein- -before set forth of thetaper shank tool having the shank longitudinally grooved, said groovebeing deeper near the shoulder than at the end of the shank, with thetool holder axially bored to receive said shank, and provided with a setkey, adapted to be forced when screwed forward.

4. A taper shank boring tool having formed in it a longitudinallygrooved key seat, inclined with relation to the axis, rearwardly andoutwardly from near the shoulder to the taper end.

MOSES L. ANDREW.

\Vitness'es:

S. R. SMITT, CHAS. BARNES.

7 into said groove for the purpose of locking the a

